# Prints out the integral input file for the PPP model of benzene.
# See Visscher and Falicov, J. Chem. Phys. 52, 4217 (1970).

# set Hamiltonian parameters
g11  =  10.72
g12  =   7.36
g13  =   5.68
g14  =   4.98
beta =  -2.50

# set number of sites
n = 6

# print number of sites
print n
print ""

# print number of irreps
print 1
print ""

# print orbital irreps
for i in range(n):
  print " 0",
print ""
print ""

# print the core energy
print "0.0"
print ""

# print overlap matrix
for i in range(n):
  for j in range(n):
    if i == j:
      print " %4i %4i %8.2f" %(i,j,1.0)
    else:
      print " %4i %4i %8.2f" %(i,j,0.0)
print ""

# print one electron integrals
for i in range(n):
  for j in range(n):
    if (i+1) % n == j or (j+1) % n == i:
      print " %4i %4i %8.2f" %(i,j,beta)
    else:
      print " %4i %4i %8.2f" %(i,j,0.0)
print ""

# print repulsion integrals
for i in range(n):
  j = (i+0) % 6
  print " %4i %4i %4i %4i %8.2f" %(i,i,j,j,g11)
for i in range(n):
  j = (i+1) % 6
  print " %4i %4i %4i %4i %8.2f" %(i,i,j,j,g12)
for i in range(n):
  j = (i+2) % 6
  print " %4i %4i %4i %4i %8.2f" %(i,i,j,j,g13)
for i in range(n):
  j = (i+3) % 6
  print " %4i %4i %4i %4i %8.2f" %(i,i,j,j,g14)
